The castle you see today is the result of 1,000 years of military occupation, beginning in Norman times. The Aragonese gave the fortress its present look in the 16th century: prior to that, a monastic community lived here. Earlier still, it was part of the estate of Roman general Lucullus. When the poet Virgil stayed here in the first century BC, local legend recounts he buried an egg (uovo), predicting that when the egg broke disaster would strike - hence the castle's name.
After crossing the bridge, pass through the main portal and either climb up to the right, or bear left along to the far end of the mole (breakwater), where the gun emplacements used to stand. It's a strangely deserted spot, with Naples almost completely hidden from view by the castle. The rooms leading off the long climb up the ramp inside the castle itself are a mix of offices and exhibition areas; some are still being excavated and restored, and for the moment are only visible through glass.